In a deep, dark menacingly thick forest there is a spring the spring is pure and clean cool and revitalizing. It is not the spring of eternal youth but it might very well be the seed of the legend.

But there is a dark truth to this fountain it is guarded by a sorceress a dark yet beautiful fairy, the creature is not evil but has her own morals and ways somebody as old and as powerful as her can allow her self such comforts

Surrounded on all sides by the thick dark forest she leads a mostly peaceful life devoting her self to her magic and rest, at one time she traveled and owned huge peaces of land and all who lived on her lands but she had grown bored and retreated to a more simple life some 4000 years ago. The 100s of miles deep forest had kept her free of any visitors for a long time now until one day.

A young man/woman (possible magic transformation from one to the other) invaded her territory lost and thirsty she/he drank from the pool and was only discovered by her afterwards. The pool gives the drinker a 100 years of extra life and since the pool is by all rights hers she demands that he/she serves these years as her servant/slave

Looking for somebody to play the lost person (Can be male or female) the general idea is that a 100 years of prolonged life should be a big deal.